The proposed project will continue to deal with the cellular pharmacology of salivary secretion with an in vitro parotid gland preparation. An attempt will be made to delineate the mechanisms by which receptors regulate second messengers such as Ca and cyclic nucleotides. The receptor mechanisms include cholinergic, peptide, alpha-adrenergic and beta-adrenergic. Additionally, the mechanisms by which these processes regulate exocytosis, and membrane permeability to other electrolytes will be sought. A combination of biophysical, biochemical and morphological approaches will be used. Biophysical studies will include flux measurements and component analysis for Ca, Na, K and Cl, the biochemical studies will examine the role of cyclic nucleotides, phospholipids, and surface receptors and the morphological approach will utilize correlated ultrastructural studies with the electron microscope. Ultimately, unifying hypotheses may be developed describing the cellular and molecular mechanisms by which autonomic agents affect cell functions and describing the basic mechanisms of salivary secretion. Such information may prove useful in the future as the role of saliva in dental health becomes more apparent.